When I first started photographing Maui’s plant life I was surprised to find that many of its most colorful and attractive plants are alien invasive species, considered to be noxious weeds and threats to native Hawaiian species and the island’s ecosystem as a whole. It’s not surprising that so many weeds have found Maui and the neighbor islands to be an ideal second home: its mild climate and tropical weather patterns are nearly identical to those of the invaders, most of whom originated in the tropical regions of South America, Africa, and Asia. Another factor contributing to the success of alien species is the numerous methods of transport and introduction to Maui’s fertile environment. Migratory birds bring in their seeds in their guts and on their feathers. Humans knowingly import them as decorative and edible species for their gardens where they often “escape” and spread to favorable neighboring habitats. Their seeds and sprouts often “hitch hike” in the cargo holds and bilge tanks of oceangoing transports. during the last century many alien species were introduced to the Islands by farmers and ranchers for use as fodder for livestock or other commercial agricultural applications.
These aggressive and opportunistic plant species are not only of interest because they pose a threat to Hawaii’s ecosystem: they are marvels of adaptation and competition, evolutionary success stories in their own rights. So for the next few postings I will cover some of the more common alien plant species that I have encountered on Maui.
Common Lantana (Lantana camara) is a fast-growing evergreen shrub that originated in the tropical islands of the Caribbean; ironically, it was brought to the Islands as an ornamental species. There are known to be more than 100 species of Lantana growing throughout the world.
The following photos were taken near Hana in eastern Maui.
L. camara foliage will grow to 6 ft (1.8 m) high and spread to as much as 8 ft (2.4 m) in width. Some varieties are vine-like and cling to any surface; however, most of the plants I’ve seen on Maui are ground-huggers, forming low, dense thickets that can aggressively crowd out other plants. The leaves are 2-5 in (5-12.7 cm) long by 1-2 in (2.5-5 cm) wide with rounded toothed edges and a textured surface. Common Lantana has been most successful in colonizing the island’s dryland forests, but I have also seen large patches growing along roadsides, in open fields and pastureland, and even in the sunnier parts of the rain forest.
Lantana is a Category I invasive exotic species known to be invading and disrupting native plant communities throughout Hawaii; it has also become a very serious threat to native plant species in Texas and Florida. It is a fast-growing shrub that is quick to set flowers and blooms year round. If it is killed out above ground by frost, it will quickly grow back and set flowers as soon as the air temperature increases. Lantana is able to tolerate a wide variety of otherwise adverse growing environments and conditions: It tolerates salt spray, relatively low air and soil temperatures, and requires only moderate sunlight and is very drought resistant. It has mechanical and chemical agents that it uses to prevent animals from eating its leaves and flowers: its stems and leaves are covered with stiff bristly hairs, and when crushed they emit an extremely unpleasant odor that has been compared to cat urine! Pets and livestock have reportedly become ill after ingesting Lantana. The unripe berries and foliage are known to be very toxic. However, when sufficiently ripened, its seed-rich berry-like fruit is attractive to birds who can safely ingest them and thus help in propagation.
Tags: Category I invasive, Hawaiian weeds, invasive species, Lantana, Lantana camara, noxious weeds, weeds
